If the federal government is going to overhaul the way mortgages are sold, I hope there’s as much emphasis put on what’s a manageable amount of debt for borrowers.

It haunts me when I think of some of the mortgage loans I’ve seen and still see. Too many people, who certainly should have known better, agreed to buy homes when their monthly mortgage payments were 50 percent to upward of 70 percent of their net pay. That’s just too much.

President Obama has laid out plans to rebuild the housing market. The plans focus on Fannie Mae and Freddie Mac, the government-backed enterprises created to help promote homeownership by increasing the availability of mortgage funds. These major housing players were taken over by the government during the financial crisis. Now, Obama says it’s time to phase out the two agencies.

“We’ve got to turn the page on this kind of bubble-and-bust mentality that helped to create this mess in the first place. We’ve got to build a housing system that is durable and fair and rewards responsibility for generations to come,” Obama said.

It doesn’t matter to me where you stand politically on the fate of Fannie and Freddie. Whether these companies stay, go or become something different, I hope the efforts to revitalize the housing market focus on people’s ability to pay their mortgage.

Obama also said something that shouldn’t be overlooked. “In the run-up to the crisis, banks and governments too often made everybody feel like they had to own a home, even if they weren’t ready and didn’t have the payments. That’s a mistake we should not repeat.”

Although homeownership is still at the heart of middle-class life, it has to come at the right time financially. When mortgage rates and home prices hit historical lows, people would ask me if they should buy a house. “Are you ready?” I asked back.

Blank stares often greeted my question. Even if you could get a zero-percent home loan for 30 years, if it eats up more than half your net pay, you probably can’t afford it. Notice I focus on net, not gross, income.

The Center for Responsible Lending recently released a gloomy report on the state of lending in America.

“Two trends are clear,” wrote Sheila Bair, a senior adviser at the Pew Charitable Trusts, in the report’s foreward. “First, families were already struggling to keep up before the financial crisis hit. The gap between stagnant family incomes and growing expenses was being met with rapidly increasing levels of debt. Second, the terms of the debt itself have acted as an economic weight and a trap, leaving families with less available income.”

Bair writes that although we’ve seen some recovery in the economy, millions of families lost their homes to foreclosure and millions more are still at risk because they are trapped “in financial marginalization.”

Despite the crisis, owning a home still has a strong hold on people. Four out of five Americans still believe that buying a home is a better financial decision than renting, the center says in its report.

As we reinvent the housing finance model, we also have to throw out old advice and lending models. Start with the way we look down on renting.

When you rent, you are not a financial failure. You are getting something for your money — a roof over your head. You also maintain flexibility when you rent, allowing you to move easily if you need to find a better-paying job in a different location.

When I traded up from my two-bedroom condominium to a single-family home, the lender said I could afford more debt than I was willing to take on. He based that decision on my financial obligations and gross income. But no one keeps all of his or her pretax income. Although I wasn’t in debt, I was taking care of my disabled brother, supplementing what little he earned. I factored this in so I would come up with a mortgage figure that left me with financial breathing room.

Whatever fix is made, don’t get a mortgage based only on the ratios used by a lender. Take it upon yourself to consider current and potential expenses that aren’t factored into a loan application. Keep your monthly housing costs, including mortgage, escrow and insurance, at about 30 percent to 36 percent of your net pay.

Consumer advocates want to make sure any changes the government makes don’t prevent creditworthy individuals from owning homes and improving their economic status. I support that mission. But I also want a more realistic approach to mortgage lending so we don’t repeat past mistakes.